Under the sponsorship of Dr. David Wong at the Harvard School of Dental Medicine, I have focused my research on the molecular cloning of cytokine genes from the Syrian hamster to study the wound healing process using the hamster as an experiment model. The model cytokine gene I cloned from the Syrian hamster is the transforming growth factor-beta 1 (TGF-b1). It is a multifunctional cytokine implicated to play central roles in wound healing. We have shown that 1) rabbit eosinophils produce TGF-a in cutaneous wounds, and 2) human eosinophils can express TGF-b1. Thus eosinophils are no longer end-stage effector cells but are capable of elaborating cytokines, regulating activities of neighboring cells and tissues. My first objective was to obtain the hamster TGF-b1 cDNA to be used as a molecular probe for detecting this cytokine gene's activity in hamster wound healing studies Cross- species cDNA cloning by the polymerase chain reaction (PCR) was used and this approach has successfully cloned hamster TGF-a cDNA in our laboratory previously. Examining the DNA matrix plot comparing the human and porcine TGF-b1 cDNAs revealed the coding sequences for the respective mature peptides are highly conserved. Three primers were designed according to human TGF-b1. Primer 1(JY- 1) was used for first strand cDNA synthesis & is located downstream to the mature peptide coding sequence at position 2134 to 2151. Primers 2 & 3(JY-2 & JY-3) flanked the mature peptide coding sequence and are located up- & downstream to it at positions 1601 to 1619 & 091-2110 respectively. This strategy amplified a 470-bp hamster TGF-b1 cDNA which includes a 336-bp sequence encoding the mature peptide. Comparison with the TGF-b1 cDNAs from human, porcine, bovine, murine, & simian revealed that the hamster TGF-b1 cDNA is 98.8, 93.8, 92, 91.7, & 97% similar respectively. The predicted amino acid sequence of the hamster TGF-b1 differs by 2 conservative changes from the other species. The availability of this cytokine, cDNA will contribute importantly towards the detection of TGF-b1 genetic activity in hamster wound healing studies. These results have been presented in the 1992 Annual Meeting of the American Association of Dental Research in Boston, MA [Yang, 1992 #1231]. With both hamster TGF-a & TGF-b1 cDNAs available, my next objective is to determine the contribution of the eosinophil-derived TGF-a & TGF-b1 in the wound healing process. I look forward to the use of these newly obtained hamster specific molecular reagents towards an in-depth understanding of this previously unnoticed leukocyte and its derived cytokines in the process of wound healing.